1. Field of the Invention
The present invention relates to a multi circuit load break switch, and more particularly, to a multi circuit load break switch configured with transistor-transistor logic (hereinafter, referred to as “TTL”) circuit elements that configuration is simple and can be fabricated with low cost.
2. Description of the Conventional Art
A multi circuit load break switch is power equipment used for the purpose of branching lines in transmission level high voltage distribution lines of several ten thousand voltage such as 22.9 kilovolt (kV) in power plants and substations.
Referring to FIG. 1, the multi circuit load break switch 1000 may be largely divided into mechanical devices including a switch 1 configured to switch a circuit to a feeding position, a breaking position or ground position and a switch actuator 2 configured to open or close three phases circuits simultaneously and switching the switch 1, and a control device configured to control the mechanical device.
Reference numeral 3 in FIG. 1 indicates a terminal bushing. As well known, the terminal bushing 3 is configured such that an electrical conductor terminal is embedded in a conical shaped insulator.
The control device can be a communication terminal device 10 and a switching control device 20 capable of opening or closing the multi circuit switch from a remote location.
An example of the circuit configuration of the control device according to the related art will be described with reference to FIG. 2.
The circuit configuration and operation of a control device will be described with reference to FIG. 2.
In FIG. 2, reference numeral 40 indicates a switch actuator circuit unit wherein a main relay 44 configured to supply or break an electric power for driving a motor as a switch actuator (refer to reference numeral 2 in FIG. 1), for instance, is a main constituent element. In FIG. 2, the switch actuator circuit unit 40 may further include an open state detection contact 41 and a closed state detection contact 42 for detecting the operation state of the switch 1, namely, an open state and a closed state, respectively. Furthermore, the switch actuator circuit unit 40 may further include a gas pressure drop detection contact 43. The gas pressure drop detection contact 43 may be configured with a normal closed contact switch configured to be open when an insulation gas pressure within the switch 1 is less than a predetermined allowable reference value and closed when it is normal.
In FIG. 2, the circuit configuration of the communication terminal device 10 will be first described.
The communication terminal device 10 may include a remote close command relay 11 and a remote open command relay 12.
The remote close command relay 11 is closed by a remote close signal (signal for remotely commanding a circuit close operation of the switch) transmitted in a pulse signal form from a monitoring device (not shown) at a remote place to perform a function for converting the remote close signal into a large-capacity direct current (abbreviated DC hereinafter) electric power source voltage (V2) signal.
Here, the large-capacity DC electric power source voltage (V2) as a relatively large DC voltage such as DC 24 volts is an operating voltage used to drive the switching control device 20 and switch actuator circuit unit 40.
The remote close command relay 11 is a close command relay having a coil magnetized by a small-capacity DC electric power source voltage (V1) and a contact closed or open according to the magnetization or demagnetization of the coil.
The remote open command relay 12 is closed in response to a remote close signal (signal for remotely commanding a circuit open operation of the switch) transmitted in a pulse signal form from a monitoring device (not shown) at a remote place to perform a function for converting the remote open signal into a large-capacity DC electric power source voltage (V2) signal.
The remote open command relay 12 is an open command relay having a coil magnetized by a small-capacity DC electric power source voltage (V1) and a contact closed or open according to the magnetization or demagnetization of the coil.
The circuit configuration of the switching control device 20 will be described with reference to FIG. 2.
The switching control device 20 may include a field closing switch 21, a field opening switch 22, a field/remote selection switch 23, a trigger relay 26, a closing relay 27, an opening relay 28, and an terminal output relay 30.
The field closing switch 21 is a switch for allowing the user to directly command the closing of the multi circuit load break switch, namely, a switching operation to a closed position at a field where the multi circuit load break switch is installed, and is connected to a voltage source of the large-capacity DC electric power source voltage (V2).
The field opening switch 22 is a switch for allowing the user to directly command the opening of the multi circuit load break switch, namely, an switching operation to an open position at a field where the multi circuit load break switch is installed, and is connected to a voltage source of the large-capacity DC electric power source voltage (V2).
The field closing switch 21 and field opening switch 22 may be configured by a push button switch.
The field/remote selection switch 23 is a selection switch for selecting whether the position manipulation of closing and opening the multi circuit load break switch is carried out by field manipulation or carried out by remote control. The field/remote selection switch 23 may be configured by two C-contact switches, and each C-contact switch has two input terminals, which are connected to the remote close command relay 11 and field closing switch 21 or the remote open command relay 12 and field opening switch 22, respectively, and the output terminal of each C-contact switch is one. The field/remote selection switch 23 transfers a signal of the large-capacity DC electric power source voltage (V2) from the remote close command relay 11, remote open command relay 12, field closing switch 21 or field opening switch 22 to the closing relay 27 or opening relay 28.
The state of the field/remote selection switch 23 illustrated in FIG. 2 is in a state that a C-contact switch connected to the remote close command relay 11 and remote open command relay 12 is selected to be connected to the field closing switch 21, and in a state that a C-contact switch connected to the remote open command relay 12 and field opening switch 22 is also selected and manipulated to be connected to the field opening switch 22.
Upon receiving a signal of the large-capacity DC electric power source voltage (V2), the trigger relay 26 transfers the signal to the closing relay 27 or opening relay 28, and demagnetizes the coil of the closing relay 27 or opening relay 28 using the signal of the large-capacity DC electric power source voltage (V2) when the open state detection contact 41 or closed state detection contact 42 of the switch actuator circuit unit 40 is closed.
Furthermore, the trigger relay 26 includes a timer for providing a predetermined period of time therewithin to automatically terminate transferring the signal of the large-capacity DC electric power source voltage (V2) to the closing relay 27 or opening relay 28 to protect the motor not to be damaged, which is a switch actuator, unless the open state detection contact 41 or closed state detection contact 42 is closed for the predetermined period of time subsequent to transferring the signal of the large-capacity DC electric power source voltage (V2), namely, when a malfunction of the open state detection contact 41 or the closed state detection contact 42 occurs. Accordingly, the coil of the relevant closing relay 27 or opening relay 28 can be demagnetized.
The closing relay 27 may include a coil connected to one output terminal of the trigger relay 26 and a contact closed or open according to the magnetization or demagnetization of the coil. Here, the input terminal of the contact is connected to an output terminal of the C-contact switch connected to the remote open command relay 12 and field opening switch 22 of the field/remote selection switch 23.
One terminal of the coil of the closing relay 27 is connected to one output terminal of the trigger relay 26, and the other terminal of the coil is connected to the open state detection contact 41.
The closing relay 27 is magnetized by a signal of the large-capacity DC electric power source voltage (V2) from the trigger relay 26 in a state that the open state detection contact 41 is closed (namely, in a state that the switch is currently open), and demagnetized when there does not exist the signal or in a state that the open state detection contact 41 is open (namely, in a state that the switch is currently closed).
The opening relay 28 may include a coil connected to the other output terminal of the trigger relay 26 and a contact closed or open according to the magnetization or demagnetization of the coil. Here, the input terminal of the contact is connected to an output terminal of the C-contact switch connected to the remote open command relay 12 and field opening switch 22 of the field/remote selection switch 23.
One terminal of the coil of the opening relay 28 is connected to one output terminal of the trigger relay 26, and the other terminal of the coil is connected to the closed state detection contact 42.
The opening relay 28 is magnetized by a signal of the large-capacity DC electric power source voltage (V2) from the trigger relay 26 in a state that the closed state detection contact 42 is closed (namely, in a state that the switch is currently closed), and demagnetized when there does not exist the signal or in a state that the closed state detection contact 42 is open (namely, in a state that the switch is currently open).
The terminal output relay 30 as a final output relay of the switching control device 20 is connected to the contacts of the closing relay 27 and the opening relay 28. The terminal output relay 30 is magnetized by a signal of the large-capacity DC electric power source voltage (V2) provided from the contact of the closing relay 27 or the opening relay 28 and demagnetized when there does not exist the signal.
The switching control device 20 may further include a closing diode 24, an opening diode 25 and a restriction switch 29.
Referring to FIG. 2, the closing diode 24 and opening diode 25 are connected between an output terminal of the field/remote selection switch 23 and an input terminal of the trigger relay 26 to transfer a signal of the large-capacity DC electric power source voltage (V2) from the field/remote selection switch 23 to the input terminal of the trigger relay 26.
The restriction switch 29 as a switch for allowing the user to break a control output from the switching control device 20 has an input terminal connected to an output terminal of the contacts of the closing relay 27 and opening relay 28 and an output terminal connected to the gas pressure drop detection contact 43.
The restriction switch 29 breaks the control output from the switching control device 20 when the user manipulates the switch 29 to an open position, and normally transfers the control output from the switching control device 20 to the terminal output relay 30 through the gas pressure drop detection contact 43 when the user manipulates the switch 29 to a closed position.
The operation of the control devices 10, 20 and the switch actuator circuit unit 40 in a multi circuit load break switch having the foregoing configuration according to the related art will be described below.
First, the operation of controlling the remote opening of the switch 1 in a state that the switch 1 of the multi circuit load break switch is currently in a closed state and the user selectively manipulates a C-contact switch connected to the remote open command relay 12 and field opening switch 22 of the field/remote selection switch 23 to be connected to the remote open command relay 12 (in a state that the location illustrated in FIG. 2 is manipulated to be switched to the other position) will be described.
When a remote opening signal transmitted in a pulse signal form from the monitoring device (not shown) is transmitted, a contact of the remote open command relay 12 is closed in response to the remote opening signal to convert the remote opening signal into a signal of the large-capacity DC electric power source voltage (V2).
Then, a signal of the corresponding large-capacity DC electric power source voltage (V2) for commanding the open operation of the switch 1 is transferred to the trigger relay 26 through a C-contact switch connected to the remote open command relay 12 and field opening switch 22 at a lower portion of the field/remote selection switch 23 in the drawing and the opening diode 25.
Since the switch 1 is currently in a closed state, the trigger relay 26 outputs a signal of the large-capacity DC electric power source voltage (V2) in a state that the closed state detection contact 42 is closed to magnetize the coil of the opening relay 28 and thus magnetizes the coil of the terminal output relay 30 through the restriction switch 29 and gas pressure drop detection contact 43 in which the signal of the large-capacity DC electric power source voltage (V2) for commanding remote open is closed while closing the contact of the opening relay 28.
Accordingly, the signal of the large-capacity DC electric power source voltage (V2) is supplied to the main relay 44 while closing the contact of the terminal output relay 30. At this time, the restriction switch 29 is in a closed position as far as the user does not manipulate it to an open position to prohibit the control output, and the gas pressure drop detection contact 43 is located at a closed position as far as an insulation gas pressure within the switch 1 is not reduced to less than a preset pressure.
As a result, electric power is supplied to the motor (not shown) which is an opening actuator while the coil of the main relay 44 is magnetized and the contact is closed, and the switch 1 in FIG. 1 is operated to an open position by the driving of the motor, thereby completing the command operation.
Next, the operation of controlling the field opening of the switch 1 in a state that the switch 1 of the multi circuit load break switch is currently in a closed state and the user selectively manipulates a C-contact switch connected to the remote open command relay 12 and field opening switch 22 of the field/remote selection switch 23 to be connected to the field opening switch 22 as illustrated in the state of FIG. 2 will be described.
When the user presses the field opening switch 22 to close the contact, the signal of the large-capacity DC electric power source voltage (V2) for commanding the open operation of the switch 1 is transferred to the trigger relay 26 through a C-contact switch connected to the remote open command relay 12 and field opening switch 22 at a lower portion of the field/remote selection switch 23 in the drawing and the opening diode 25, and the subsequent operation will be carried out in a similar manner to the foregoing operation of controlling the remote opening of the switch 1, and thus the description of redundant description will be omitted.
Next, the operation of controlling the field closing of the switch 1 in a state that the switch 1 of the multi circuit load break switch is currently in an open state and the user selectively manipulates a C-contact switch connected to the remote close command relay 11 and field closing switch 21 of the field/remote selection switch 23 to be connected to the field closing switch 21 as illustrated in the state of FIG. 2 will be described.
When the user presses the field closing switch 21 to close the contact, the signal of the large-capacity DC electric power source voltage (V2) for commanding the close operation of the switch 1 is transferred to the trigger relay 26 through a C-contact switch connected to the remote close command relay 11 and field closing switch 21 at an upper portion of the field/remote selection switch 23 in the drawing and the closing diode 24.
Since the switch 1 is currently in an open state, the trigger relay 26 outputs a signal of the large-capacity DC electric power source voltage (V2) in a state that the closed state detection contact 42 is closed to magnetize the coil of the closing relay 27 and thus the signal of the large-capacity DC electric power source voltage (V2) for commanding remote open magnetizes the coil of the terminal output relay 30 through the restriction switch 29 and gas pressure drop detection contact 43 which are closed while closing the contact of the closing relay 27.
Accordingly, the signal of the large-capacity DC electric power source voltage (V2) is supplied to the main relay 44 while closing the contact of the terminal output relay 30. At this time, the restriction switch 29 is in a closed position as far as the user does not manipulate it to an open position to prohibit the control output, and the gas pressure drop detection contact 43 is located at a closed position as far as an insulation gas pressure within the switch 1 is not reduced to less than a preset pressure.
As a result, electric power is supplied to the motor (not shown) which is an opening actuator while the coil of the main relay 44 is magnetized and the contact is closed, and the switch 1 in FIG. 1 is operated to a close position by the driving of the motor, thereby completing the command operation.
Next, the operation of controlling the field closing of the switch 1 in a state that the switch 1 of the multi circuit load break switch is currently in an open state and the user selectively manipulates a C-contact switch connected to the remote close command relay 11 and field closing switch 21 of the field/remote selection switch 23 to be connected to the remote close command relay 11 from the state illustrated in FIG. 2 will be described.
When a remote closing signal transmitted in a pulse signal form from the monitoring device (not shown) is transmitted, a contact of the remote close command relay 11 is closed in response to the remote closing signal to convert the remote closing signal into a signal of the large-capacity DC electric power source voltage (V2).
Then, a signal of the large-capacity DC electric power source voltage (V2) for commanding the close operation of the switch 1 is transferred to the trigger relay 26 through a C-contact switch connected to the remote close command relay 11 and field closing switch 21 at an upper portion of the field/remote selection switch 23 in the drawing and the closing diode 25. The subsequent operation will be carried out in a similar manner to the foregoing operation of controlling the field closing of the switch 1, and thus the description of redundant description will be omitted.
A control device of a multi circuit load break switch operated by the foregoing configuration according to the related art has a problem as described below.
In other words, a control device of a multi circuit load break switch according to the related art may use electrical circuit constituent elements other than electronic circuit constituent elements using a large-capacity DC electric power source voltage above DC 24 volts, and have a high rated voltage and thus the size and cost of the constituent elements may be larger and higher than those of the electronic elements, thereby increasing the cost of manufacturing the control device and the size thereof.
Furthermore, a control device of a multi circuit load break switch according to the related art may have a configuration in which the communication terminal device 10 and switching control device 20 are separately provided, and connected to each other by signal cables, and thus a lot of complicated signal cables may be wired, thereby causing inconvenience in the maintenance as well as increasing the space occupied by the multi circuit load break switch.